Photoelectric time switching control



Jan. l6, 1951 R. o. RITCHIE ET AL 5 5 PHOTOELECTRIC TIME SWITCHING (TONTROL Filed Aug. 28 1948 9 39 )2 35 i 2O Vohs A.C.

4O Conrrolled OuTpur 36: 2O 46 47 2O 1 G. 26 L--- .J 2 L lag gm 8 In M" p L L 25 24 INVENTORS ROBERT 0. RITCHIE STANLEY MITCHELL ATTORNEY Patented Jan. 16, 1951 I anemones-mm Tm Robert 9, Momymmeme San Gehzieyfiflif,

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1131 the genteel eireuit'whiehreceives-powerh t 5 I v A A Q V is fiehb e te unit and e m translate -elee licat z esieiame 4, jngajfiigflefl fromtheiight-sensitive unitintoa creases, changing the voltage relgti gngm -p action. in the cireuit illustrated, vthe tween 2 h? :QDEFZIQJ firm ,33 31nd the thqde 3| e-mbejhing unitfisanelectromagnetie relay whose be thy; n I, gntil p late action is controlled b-ya triads-gas dischavgetube-"fifi tigp of 1; wQith'jnd-iregiyheated-cathode (th-yratmn) which 3mm; g isg ni rfil fi t y a h wmheworiti hk "device. wee thyi eitaiori'tube :H gs bro- M W hag {9 an indirect heating efiement 1-2 ewmeh he m le :9! we eee e,

idler/ink deeeriptien, iefef e e; ma mas em m e nmn ement of the erleetr kal ti e it (photo-tube No. 929), the resistors 36 (6,000

ohms) and 31 (5 megohms), the potentiometer 35 (3,000 ohms maximum), resistors 43 (6000 ohms) and 44 (350 ohms), and the cathode 3!. The element [2 of the gas discharge tube II (thyratron 2050 or GL 502A)'is energizedand The light striking the photo-tube 38 gradually decreases with the passheats the cathode 3|.

ing time of day and with it the resistance of the photo-tube increases, until the voltage on the grid 33 allows plate current to pass. When the required current passes through the plate circuit and through the electromagnetic coil 2| of the-relay to overcome its inertia-the movable arms and 20A are moved'to'the opposite positions from those shown in the diagram (1. e. to the right). This 'movement of the relay switches causes three changes in the system: (1) the output circuit line 29 is connected through the arm 20 and the contact 46, through the. time clock and 23 and the contact 22 to the input circuit line 25, thus applying voltage to the controlled circuit; (2) the coil of the relay is connected to the input circuit line through the arm 20A and switch contact 4Bso that it no longer depends on theplate current from the thyratron gas discharge tube I I and any further changes in light intensity either short flashes or of longer duration have no effect on the relay or on the photo-cell circuit until the time clock has again turned over control of the photoelectric cell; (3) current to the heater element I2of the tubell. and photo-fcell circuit is disconnected by'the arm 20A at the switch contactA'l: a P

.When the time clock reacheslthefturn oil,

position, moving off the contact 22,-voltage is shut oil from the relay coil circuit, the relay "opens, and the output circuit is de-energized.

The relay, electronic components and output circuit will remain Lie-energized until the time clock again reaches the selected turn-on position, and contact i made again between the movable arm 23 and the contact 22. The power output circuit will remain ole-energized after the clock has turned on until the incident light intensity on the photo cell 38 has decreased beyond the pre selected intensity, which is'controlled by the-"setting of the potentiometer contact 39.

' It will be noted that the electronic circuit is in operation only in the interval between the turmoil time by the time clock and the attainment of suiiiciently decreased light intensity so that the plate current through the thyratron gas discharge tube closesth relay, as described. This is advantageous in reducing current consumption and in the longer effective life of the elements in the'circuit.

Y The advantages of the invention will be apparlevel where output is desired. The output is shut off at a selected clock time, regardless of the length of time it'has been turned on. The sen- 4 sitive instruments in the circuit are in use for only a short period of time each day, and therefore have long life and require little servicing. This is most important in controlling sign lighting, etc. The arrangement is simple, relatively inexpensive, and its use conserves electrical energy by turning on the power output circuit only when needed, and turning it off when aselected time by the clock has been reached.

While particular embodiments have been used to illustrate the invention, it will be understood that various modifications may be made without departing from the spirit and scope of this invention as defined in the following claims.

We claim:

1. In combination with an input power circuit and an output power circuit, a light sensitive electrical device control circuit, a relay switch controlled by said control circuit, a holding circuit for said relay switch, said holding circuit being kept closed by said relay switch, and a time clock switch, said time clock switch being set to allow current to flow from said input circuit only during a selected interval of time, said relay switch being closed at times by said light sensitive electrical device control circuit and for the succeeding time being held closed by said holding circuit energized by said input power circuit, flowing through said time clock switch during said selected interval of time.

2. In combination with an'input power circuit and an output power circuit, "a light sensitive control circuit comprising a triode gas conduction celljhaving a control" grid and a photo-cell circuit adapted to control the flow of current through said triode cell by the variable voltage impressed upon said grid in response to varying light intensities on the photo-cell of said photoshutting off of said input power circuit by said time clock switch. I v

3. In combination with an input, powercircuit and an output power circuit a light sensitive control circuit comprisin a triode gas conduction cell having a control grid anda photo-cell circuit adapted to; control the flow of current through said triode cell by the variable voltage impressed upon said gridin response to varying light intensities on the photo-cell of said photo-cell circuit, a relay switch adapted to be closed at times by said current through said triode cell; a holding circuit for said relay, said holding circuit being kept closed by said relay switch and a time clock switch providing over-riding control over said photo-cell circuit and said output power circuit, said clock switch being set to allowcurrent to flow from said input circuit only during a selected interval of time, said relay switch being held in closed position by said holding circuit after initial energization by said current through said-triode cell until released by the shutting'ofi ofsaid input power circuit by said time clockswitch, said relay switch in closed position shuttingfoff energizing current to said triode cell and said vphoto-cell circuit, :and applying voltage to said output circuit.

4. Automatic electric output circuit switching control means comprisin a photosensitive electrical device, a triode gas conduction tube, a double pole electromagnetic relay switch, a time clock switch, and an input electrical circuit, said photo-sensitive electrical device being adapted to be subjected to light of varying intensity, said device under a seletced light intensity being adapted to impress an electrical charge on the grid controlling the flow of current between the heated cathode and the plate of said triode gas conduction tube, said fiow of current arranged in a circuit adapted to close said double-pole electromagnetic relay switch, said relay switch when closed connecting the coil of said electromagnetic relay to said input circuit independent a selected light intensity being adapted to impress an electrical charge on the grid controlling the flow of current between the heated cathode and the plate of said triode gas conduction tube, said flow of current being arranged in a circuit adapted to close said double pole electromagnetic relay switch, said relay switch when closed connectin the coil of said electromagnetic relay to said input circuit independent of said triode tube circuit, and disconnecting said photoelectric device including the heating circuit of said triode cell, and said relay switch also connecting and disconnecting said output circuit, said input circuit being connected and disconnected at selected time intervals by said time clock switch.

ROBERT O. RITCHIE. STANLEY MITCHELL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

